Data Structures | |
struct | qof_entity_reference |
External references in a partial QofBook. More... | |
Files | |
file | qofreference.h |
Dealing with relationships between entities in partial books. | |
Using a partial QofBook. | |
Part of the handling for partial books requires a storage mechanism for references to entities that are not within reach of the partial book. This requires a GList in the book data to contain the reference QofIdType and GUID so that when the book is written out, the reference can be included. See qof_book_get_data. When the file is imported back in, the list needs to be rebuilt. The QSF backend rebuilds the references by linking to real entities. Other backends can process the list in similar ways. The list stores the QofEntityReference to the referenced entity - a struct that contains the GUID and the QofIdType of the referenced entity as well as the parameter used to obtain the reference.
Partial books need to be differentiated in the backend, the flag in the book data is used by qof_session_save to prevent a partial book being saved using a backend that requires a full book. Forcing this flag would cause data loss so always merge a partial book with the complete book (even if that book is initially empty) before trying to save the data using a backend that does not support partial books. | |
typedef struct qof_entity_reference | QofEntityReference |
External references in a partial QofBook. | |
void | qof_session_update_reference_list (QofSession *session, QofEntityReference *reference) |
Adds a new reference to the partial book data hash. | |
void | qof_book_set_references (QofBook *book) |
Read QofEntityReference data for this book and set values. | |
QofEntityReference * | qof_entity_get_reference_from (QofEntity *ent, const QofParam *param) |
Get a reference from this entity to another entity. | |
#define | ENTITYREFERENCE "QofEntityReference" |
#define | PARTIAL_QOFBOOK "PartialQofBook" |
Flag indicating a partial QofBook. |
Partial books are useful for query results, selective export and data mining but need to be merged back into standard books. It is not supported to construct a partial book and then convert the same book to a standard book.
Different backends have different requirements for a complete book - some (like gnucash) are highly customised to that application - however all complete QofBooks must be self-contained, only a partial book uses QofEntityReference.
To retain the relationships between entities, including between a partial and a complete book, QofEntityReference data is stored in the QofBook. This data should be read by backends that support partial books so that the exported data contains the GUID and QofIdType of the referenced entity. Even if that entity does not then exist within the partial book, it can be located when the partial book is merged back into the original, complete, book. (Remember that given the GUID and QofIdType of any QofEntity it is possible to uniquely identify that entity in another book.)
Entities in partial books may need to refer to the entities that remain within the partial book. Once all the entities you want are in the partial book, call qof_book_set_references to restore as many references as possible. Each object type is checked in turn, each entity of that type and then each parameter that can relate to another entity. Any references that cannot be found are left unset - depending on the object these may be undefined or NULL. (It is advisable to set all QOF parameters to either a default value or NULL in the create: routine for the object but QOF has no way of guaranteeing this.)
#define ENTITYREFERENCE "QofEntityReference" |
Used as the key value for the QofBook data hash.
Retrieved later by QSF (or any other suitable backend) to rebuild the references from the QofEntityReference struct that contains the QofIdType and GUID of the referenced entity of the original QofBook as well as the parameter data and the GUID of the original entity.
Definition at line 137 of file qofreference.h.
#define PARTIAL_QOFBOOK "PartialQofBook" |
Flag indicating a partial QofBook.
When set in the book data with a gboolean value of TRUE, the flag denotes that only a backend that supports partial books can be used to save this session.
Definition at line 146 of file qofreference.h.
typedef struct qof_entity_reference QofEntityReference |
External references in a partial QofBook.
For use by any session that deals with partial QofBooks. It is used by the entity copy functions and by the QSF backend. Creates a GList stored in the Book hashtable to contain repeated references for a single entity.
void qof_book_set_references | ( | QofBook * | book | ) |
Read QofEntityReference data for this book and set values.
book | The partial book containing the referenceList |
The referenceList is used in partial books to store relationships between entities when the entities themselves might not exist in the partial book.
If the book is not marked as a partial book, an assertion error is generated.
This routine tries to lookup each entity in the referenceList for the book and then tries to lookup the reference - to find the child entity that was originally linked to this parent. The child entity is then set in the parent so that it can be located as normal.
If the child entity does not exist in this partial book, the parent entity is not updated. The referenceList is unchanged (in case the child is added later).
Definition at line 177 of file qofreference.c.
00178 { 00179 gboolean partial; 00180 00181 partial = 00182 (gboolean) 00183 GPOINTER_TO_INT (qof_book_get_data (book, PARTIAL_QOFBOOK)); 00184 g_return_if_fail (partial); 00185 qof_object_foreach_type (set_each_type, book); 00186 }
QofEntityReference* qof_entity_get_reference_from | ( | QofEntity * | ent, | |
const QofParam * | param | |||
) |
Get a reference from this entity to another entity.
See also qof_class_get_referenceList to obtain the list of parameters that provide references to the known entity whilst excluding parameters that return known QOF data types.
Note that even if the referenced entity exists in the partial book (or will exist later), a reference must still be obtained and added to the reference list for the book itself. This maintains the integrity of the partial book during sequential copy operations.
ent | The known entity. | |
param | The parameter to use to get the referenced entity. |
Definition at line 167 of file qofreference.c.
00168 { 00169 g_return_val_if_fail (param, NULL); 00170 param = qof_class_get_parameter (ent->e_type, param->param_name); 00171 g_return_val_if_fail (0 != 00172 safe_strcmp (param->param_type, QOF_TYPE_COLLECT), NULL); 00173 return create_reference (ent, param); 00174 }
void qof_session_update_reference_list | ( | QofSession * | session, | |
QofEntityReference * | reference | |||
) |
Adds a new reference to the partial book data hash.
Retrieves any existing reference list and appends the new reference.
If the book is not already marked as partial, it will be marked as partial.
Definition at line 234 of file qofsession.c.
00236 { 00237 QofBook *book; 00238 GList *book_ref_list; 00239 00240 book = qof_session_get_book (session); 00241 book_ref_list = (GList *) qof_book_get_data (book, ENTITYREFERENCE); 00242 book_ref_list = g_list_append (book_ref_list, reference); 00243 qof_book_set_data (book, ENTITYREFERENCE, book_ref_list); 00244 qof_book_set_partial (book); 00245 }